Have you looked at the Patagonia Stormfront Hip Pack? I realize it is called a Hip Pack, but I think I heard you could wear it up around your chest. However, Fishpond's Westwater Chest Pack is very nice and much cheaper. I have a San Juan Chest Pack and love it, but kind of wish I had the Westwater.
I find your comment about the waterproof fly boxes interesting. I have two waterproof C&F boxes, and have never had the first issue with them.